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Author : Chengxi Shen
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (995 download)
Download or read book The High Frequency Surface Wave Radar Cross Section for Ocean Swell written by Chengxi Shen and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 42 pages
Book Rating : 4.:/5 (227 download)
Download or read book Radar Cross Section Calculations of Traveling Surface Waves written by and published by . This book was released on 1990 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: The traveling surface wave phenomenon, a significant echo mechanism for long, smooth bodies, manifests itself in the radar cross section (RCS) pattern of realistic targets for horizontal polarization and grazing angles of incidence. Existing radar cross section models do not take this scattering mechanism into account because none of the presently available theories and methods can treat traveling waves in routine fashion (see E.F. Knott, A progression of High-Frequency RCS prediction Techniques, Proc., IEEE, Vol. 73, No. 2 pp. 252-264(Feb 1985). Analytical radar cross section models for realistic targets should include this type of scattering in their calculations. This report presents a theory and an efficient method for calculating traveling surface wave contributions on a thin rod and an ogive of arbitrary length. Rectangular flat plate radiation patterns are also briefly considered. The details and necessary expressions for predicting RCS of plates will be given in a future report, where the approach will be extended to a more complex target. The theoretical approach presented here is based on the existing concepts of antenna theory and geometrical theory of diffraction. Radar cross section patterns that include traveling wave contributions for a rectangular flat plate and a rod of equal length are calculated and compared with measurements. The theoretical results and measured data show very good agreement.
Author : Mikhail B. Kanevsky
Publisher : Elsevier
ISBN 13 : 0080932517
Total Pages : 207 pages
Book Rating : 4.0/5 (89 download)
Download or read book Radar Imaging of the Ocean Waves written by Mikhail B. Kanevsky and published by Elsevier. This book was released on 2008-09-15 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is dedicated to studying the ocean with radar tools, in particular, with space radars. Being intended mainly for the scientists preoccupied with the problem (as well as senior course students), it concentrates and generalizes the knowledge scattered over specialized journals. The significant part of the book contains the results obtained by the author. Systematically collects and describes the approaches used by different laboratories and institutions Deals with the physics of radar imagery and specifically with ocean surface imagery Useful for students and researchers specializing in the area of ocean remote sensing using airborne or space-borne radars, both SAR and RAR
Author : Murilo Teixeira Silva
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (131 download)
Download or read book Generalized Functions Approach to the Derivation of the High-frequency Radar Cross-section of Ocean Surfaces with Electromagnetically-large Waves written by Murilo Teixeira Silva and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The radar cross-section (RCS) of the ocean surface mathematically describes the interaction between electromagnetic fields and ocean waves, allowing for a better understanding of observations made by coastal high-frequency (HF) radars. However, theoretical limitations have restricted the calculation of the RCS of the ocean surface to electromagnetically-small waves. This thesis proposes an approach to study and evaluate the scattering of electric fields over ocean surfaces with electromagnetically-large waves, as well as an extension of the generalized functions approach to the one-body scattering problem to curvilinear coordinates with variable basis vectors. The present work enables the analysis of HF radar signals scattered by the ocean surface during storms and electromagnetically-high sea states, expanding the capabilities of HF radars in radio oceanography. First, a system of equations for the electric field in curvilinear coordinates in the presence of a single scatter is proposed. It is shown that the derived equations can be applied to coordinate systems with variable basis vectors, being reduced to the form presented in the literature [1] when Cartesian coordinates are considered. As a proof of concept, the system of equations for curvilinear coordinates is applied to a perfectly-electrically conductive (PEC) sphere, yielding the Stratton-Chu integral equation for the electric field, a general solution in classic electromagnetics. Then, the electric field scattering over a time-varying conductive random surface is obtained for an ocean surface with electromagnetically-large waves. First, the electric field expressions are obtained by applying the proposed system of equations to a time-varying conductive random surface, removing the restrictions to the growth of the roughness scales presented in the literature. This allows for the study of ocean surfaces with electromagnetically-large waves. The derivation results in additional electric field expressions that correct the height-restricted expression accounting for the energy of electromagnetically-large waves. The resulting expression is reduced to the height-restricted formulation if the roughness scale is sufficiently small. From the expression of the electric field, the RCSs of the correction terms are derived. These derivations yield expressions that can be reduced to a general form, allowing the generation of correction terms to the radar cross-section at a given order by a product with the desired correction factor. In a morphological analysis of the correction factors, it is shown that at small roughness scales, the correction terms do not affect the total cross-section for the ocean surface; however, by increasing the roughness scale beyond the limits presented in the literature, the contribution of the correction terms to the total RCS become significant. Evidence of the presence of the proposed correction terms was approved in field measurements; however, definitive proof of the effects observed here can be the object of future research.
Author : G.L. Geernaert
Publisher : Springer Science & Business Media
ISBN 13 : 9400906277
Total Pages : 378 pages
Book Rating : 4.4/5 (9 download)
Download or read book Surface Waves and Fluxes written by G.L. Geernaert and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the Conference on Air-Sea Interaction in January 1986, it was suggested to me by David Larner of Reidel Press that it may be timely for an updated compendium of air-sea interaction theory to be organized, developed, and published. Many new results were emerging at the time, i.e., results from the MARSEN, MAS EX, MILDEX, and TOWARD field projects (among others) were in the process of being reported and/or published. Further, a series of new experiments such as FASINEX and HEXOS were soon to be conducted in which new strides in our knowledge of air-sea fluxes would be made. During the year following the discussions with David Larner, it became apparent that many of the advances in air-sea interaction theory during the 1970s and 1980s were associated with sponsor investments in satellite oceanography and, in particular, remote sensing research. Since ocean surface remote sensing, e.g., scatterometry and SAR, requires intimate knowledge of ocean surface dynamics, advances in remote sensing capabilities required coordinated research in air-sea fluxes, wave state, scattering theory, sensor design, and data exploitation using environmental models. Based on this interplay of disciplines, it was decided that this book be devoted to air sea interaction and remote sensing as multi-disciplinary activities.
Author : Yue Ma
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (132 download)
Download or read book Bistatic High Frequency Radar Ocean Surface Cross Section for an Antenna on a Floating Platform written by Yue Ma and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Land-based high frequency surface wave radar (HFSWR) is an established sensor for ocean remote sensing. Placing an HFSWR on a floating platform has the advantage of mobility. However, antenna motion will distort the Doppler spectrum, which is used to extract ocean information and to detect the signatures of targets. In this thesis, significant effort has been expended on establishing radar cross section (RCS) models for a fixed receiver and a transmitter on a floating platform, analyzing the effect of the antenna motion, and developing a motion compensation method to eliminate the effect of the platform motion. The first- and second-order monostatic RCSs of the ocean surface for the case of a pulsed dipole source on a floating platform have been previously derived in the literature, with the assumption that the platform motion is a single-frequency sinusoid. Following that work, the research in this thesis is extended to the bistatic case. The effect of platform motion on simulated Doppler spectra is considered for a variety of sea states. It is shown that the resulting motion-induced peaks are symmetrically distributed in the Doppler spectrum. Following this work, the corresponding bistatic RCS models for a frequency modulated continuous waveform (FMCW) source are derived. Results show that the sidelobe level for an FMCW source is reduced with increasing extent of range bin. To mimic real world scenarios, platform motion is next modelled as a combination of two cosine functions, based on existing research of realistic horizontal motions of moored floating platforms. RCSs incorporating a dual-frequency platform motion model are then developed. These can be extended to a general form incorporating a multi-frequency platform motion. It is found that the platform motion can be viewed as a modulator of the radar frequencies, with the modulation indices related to the amplitudes of the platform motion. Finally, to mitigate the effect of platform motion on the Doppler spectra, a motion compensation method is proposed. This motion compensation method can be achieved by a deconvolution process. Calculations involving a RCS model, incorporating external noise, for an antenna on a floating platform are conducted in order to simulate field data and to examine this motion compensation method. The external noise is characterized as a white Gaussian zero-mean process. By using this newly-developed RCS model with external noise, motion compensation results under different sea states and signal-to-noise ratios (SNRs) are examined. The outcomes indicate that an iterative Tikhonov regularized deconvolution technique is superior to other compensation methods implemented in this study.
Author :
Publisher :
ISBN 13 :
Total Pages : 7 pages
Book Rating : 4.:/5 (742 download)
Download or read book An Estimation and Verification of Vessel Radar-Cross-Sections for HF Surface Wave Radar written by and published by . This book was released on 2005 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The radar cross sections (RCS) of both small and large ships for High Frequency Surface Wave Radar (HFSWR) were studied by using Numerical Electromagnetics Code [4] and by using measurements from a HFSWR system at Cape Race, Newfoundland, Canada. The results of the study indicate that Teleost, a 2405-ton Canadian Coast Guard ship, and large cargocontainer vessels (~36000 ton) have comparable RCS values at 3.1 and 4.1 MHz. This was verified by comparing Teleost signals with the reflections of seven cargo-container vessels identified during an operational evaluation of the HFSWR. The conclusion of the study is that Teleost and the large cargo-container vessels have an angle-averaged RCS of ~40dBm2, while small vessels (~1000 tons) could reasonably be characterized by an angle-averaged RCS of ~30 dBm2, in the lower end of the HF band (3-5 MHz).
Author : Belinda J. Lipa
Publisher :
ISBN 13 :
Total Pages : 70 pages
Book Rating : 4.3/5 (91 download)
Download or read book Analysis Methods for Narrow-beam High-frequency Radar Sea Echo written by Belinda J. Lipa and published by . This book was released on 1982 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : George T. Ruck
Publisher :
ISBN 13 :
Total Pages : 504 pages
Book Rating : 4.:/5 (43 download)
Download or read book Radar Cross Section Handbook written by George T. Ruck and published by . This book was released on 1970 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : E. A. Caponi
Publisher :
ISBN 13 :
Total Pages : 68 pages
Book Rating : 4.:/5 (227 download)
Download or read book Modulation of Radar Backscatter from the Ocean by a Variable Surface Current written by E. A. Caponi and published by . This book was released on 1988 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Calculations of surface wave and radar cross section modulation induced by a spatially varying surface current have been compared with field measurements made with SAR (X- and L-bands), real aperture radar (X-band), laser slope guage, and CCD video camera during the Joint Canada/U.S. Ocean Wave Investigation Project (JOWIP) which took place in August 1983. The comparison reveals that (i) many existing wind-relaxation models underpredict the hydrodynamic effect of the current, (ii) simple Bragg scattering model underpredicts radar backscatter modulation for higher frequency radars (e.g., X-band) but appears acceptable at lower radar frequencies (e.g., L-band), (iii) the discrepancy between measurements and calculations at high radar frequency is reduced, but not eliminated, when the effects of long surface waves have been accounted for. Keywords include: Radar backscatter, Surface wave modulations, Wave-current interactions, Georgia strait experiment, and JOWIP. (RRH).
Author :
Publisher :
ISBN 13 :
Total Pages : 456 pages
Book Rating : 4.:/5 (3 download)
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author : Ming Hung
Publisher : BoD – Books on Demand
ISBN 13 : 1789235367
Total Pages : 216 pages
Book Rating : 4.7/5 (892 download)
Download or read book Recent Advances and Applications in Remote Sensing written by Ming Hung and published by BoD – Books on Demand. This book was released on 2018-07-25 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: Remote sensing was the primary data source since the launch of the first environmental monitoring satellite back in 1972. In the past five decades, remote sensing technology has come a long way and evolved into a mature science. Even so, new technologies, new theories, new methodologies, and new applications continue to emerge. With the rapid pace of technological advancement, it is essential to share experiences especially between different disciplines, either on breakthroughs in new theory or understanding, or applications of remote sensing on real world issues. Disciplines or fields covered in this book include geography, geology, agriculture, forestry, botany, and oceanography. Though remote sensing may be used differently in various disciplines, the principles are similar, if not the same. This book will be valuable to scientists, scholars, working professionals, or students who use remote sensing in their work, and are interested in learning how others use remote sensing in different ways.
Author : D. B. Trizna
Publisher :
ISBN 13 :
Total Pages : 25 pages
Book Rating : 4.:/5 (227 download)
Download or read book Estimation of the Sea Surface Radar Cross Section at HF from Second-Order Doppler Spectrum Characteristics written by D. B. Trizna and published by . This book was released on 1982 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: A technique is developed for estimating the radar cross section of the sea surface at HF (2-30 MHz) from two simple measurements made of the radar Doppler spectrum. These are: the ratio of approach/recede Bragg line energy, and the ratio of strongest Bragg line amplitude to average value amplitude of second-order backscatter at zero Doppler frequency. A nomograph is given, based on a theoretical model of second-order scatter developed by the author, which then allows one to determine the number of decibels the Bragg ocean spectral component is down from the classical Phillips asymptotic value, used here only for a reference. Comparison is made with some surface wave data for three different cases in which buoy data are available for comparison with multi-frequency radar data collected simultaneously at two different look angles. An example is also shown where such a calculation can be used to estimate the cross section of a target return existing within the same Doppler spectrum. Limitations of the technique are also discussed. (Author).
Author : Hany Mohamed Assal
Publisher :
ISBN 13 :
Total Pages : 118 pages
Book Rating : 4.:/5 (318 download)
Download or read book Measurements of Ocean Surface Waves Using Synthetic Aperture Radar written by Hany Mohamed Assal and published by . This book was released on 1981 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : S. Barkeshli
Publisher :
ISBN 13 :
Total Pages : 196 pages
Book Rating : 4.:/5 (227 download)
Download or read book Interaction of the Radar Waves with the Capillary Waves on the Ocean written by S. Barkeshli and published by . This book was released on 1983 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of the radar cross-section of the sea were made from the Noordwijk platform off the Dutch coast during September-November 1979 as part of Project MARSEN using an FM microwave spectrometer over the 8-18 GHz frequency range. A set of techniques for studying the modulation of the capillary waves on the ocean surface was developed for use in analyzing the entire observation set and is presented here as applied to a single set of observations. Thus, the results given here are only of limited oceanographic significance, but illustrate the types of analysis to be performed when these techniques are applied to more data. Measured scattering coefficient based on instantaneous radar footprint was cross-correlated with wave height and slope for measurements at the Noordwijk tower on 21 September 1979.
Author :
Publisher : Academic Press
ISBN 13 : 0080568564
Total Pages : 540 pages
Book Rating : 4.0/5 (85 download)
Download or read book Advances in Geophysics written by and published by Academic Press. This book was released on 1985-08-01 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Geophysics
Author : United States. Department of Commerce
Publisher :
ISBN 13 :
Total Pages : 72 pages
Book Rating : 4.:/5 (319 download)
Download or read book The United States Department of Commerce Publications, Catalog and Index Supplement written by United States. Department of Commerce and published by . This book was released on 1966 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:
